No, a battery charger doesn't always have to be connected directly to the battery. The way you connect a battery charger depends on the type of charger you're using and the situation you're in. There are generally two common ways to connect a battery charger:    

**1. Direct Connection to Battery Terminals:**
This is the most common method and involves connecting the charger's positive and negative clamps directly to the battery terminals. This allows the charger to supply charging current directly to the battery for charging.

**2. Accessory Outlet (Cigarette Lighter) Connection:**
Some battery chargers, often referred to as "trickle chargers" or "maintainers," are designed to be plugged into the vehicle's accessory outlet (cigarette lighter) rather than connected directly to the battery terminals. These chargers are typically used for maintaining the battery charge during periods of inactivity, such as when a vehicle is parked for a long time.

It's important to note that the effectiveness of using an accessory outlet charger can vary. These chargers are generally designed for smaller batteries like those found in motorcycles, lawnmowers, or small vehicles. They might not be as efficient for larger vehicle batteries or in situations where the battery is significantly discharged.

When using a direct connection charger, be sure to follow safety guidelines, such as wearing protective gear, ensuring proper polarity (connecting positive to positive and negative to negative), and working in a well-ventilated area.

Always refer to the manufacturer's instructions and guidelines for your specific battery charger and vehicle to ensure safe and effective charging.